The Mitotic Cell Cycle Flashcards
Describe the structure of chromosomes
Chromosomes> chromatids/ sister chromatids> chromatins > DNA > genes
What are chromatins and describe it’s structure.
Tightly coiled combination of DNA and proteins; What chromatids, and therefore chromosomes are made up of.
Structure:
1. Consist of a very long, condensed DNA molecule associated with proteins.
What are the proteins involved in chromatin structure and describe their roles.
- Main protein: large, positively charged globular proteins called HISTONES
ROLE: to ORGANISE and CONDENSE the DNA tightly so that it fits into the nucleus
- Other proteins are enzymes involved in copying and repairing DNA
What are chromatids?
- One of two identical parts of a chromosome.
- Held together by centromere
- formed during interphase( S PHASE) by the replication of the DNA strand.
- two identical chromatids ( sister chromatids) make one chromosome. •Each chromatids contains one, very long DNA molecule, which is made up of a series of genes
Note: no genes are found in the centromere.
Why must sister chromatids be genetically identical?
It’s the key to cell division, as one chromatic goes into one daughter cell and one goes into the other daughter cell during mitosis, ensuring the daughter cells are genetically identical
What are telomeres?
Protective structures that seal the ends of the chromatids in chromosomes.
What is mitosis?
The process of nuclear division by which two genetically identical daughter nuclei are produce that are also genetically identical to the parent nuclei (Have exactly the same number and type of chromosomes as the parent cell)
Describe the role of mitosis in the growth of multicellular organisms.
- The two daughter cells produced aee genetically identical to one another [clones] and have the same number of chromosomes as the parent cell.
- This enables unicellular zygotes [as the zygote divides by mitosis] to grow into multicellular organisms.
Describe the role of mitosis in the replacement of cells and repair of tissues
- Damaged tissues can be repaired by mitosis followed by cell division
- As cells are Constanly dying they need to be continuously replaced by genetically identical cells.
What is asexual reproduction?
The production of genetically identical offsprings from a single parent organism
Describe the role of mitosis in the asexual reproduction in unicellular and multicellular organisms
Unicellular organisms (e.g Amoeba): cell division results in the production of a genetically identical offspring.
Multicellular organism:
Budding: a form of vegetative propagation.
• new individuals grow from the parent organism (e.g paru of a stem) and then bud off from the parent in various ways and lives independently.
Examples: hydra, yeast and runners from strawberries.
Describe the role of mitosis in immune response
The cloning of B and T lymphocytes during immune response is dependent on mitosis
